17 October 2008

Nattō (なっとう or 納豆, Nattō) is a traditional Japanese food made from fermented soybeans, popular especially for breakfast. As a rich source of protein, nattō and the soybean paste miso formed a vital source of nutrition in feudal Japan.

It is often said in Japan that nattō is good for one's health, and these claims can be backed by medical research. One example is Pyrazine contained within nattō. Pyrazine is a compound which, in addition to giving nattō its distinct smell, reduces the likelihood of blood clotting. It also contains a serine protease type enzyme called nattokinase which may also reduce blood clotting both by direct fibrinolysis of clots, and inhibition of the plasma protein plasminogen activator inhibitor 1. This may help to avoid thrombosis, as for example in heart attacks, pulmonary embolism, or strokes. An extract from nattō containing nattokinase is available as a dietary supplement. Studies have shown that oral administration of nattokinase in enteric capsules leads to a mild enhancement of fibrinolytic activity in rats and dogs. It is therefore plausible to hypothesize that nattokinase might reduce blood clots in humans, although clinical trials have not been conducted. Another study suggests the FAS in natto is the substance which initiates fibrinolysis of clots, which accelerates the activity of not only nattokinase but urokinase.

Nattō also contains large amounts of Vitamin K, which is involved in the formation of calcium-binding groups in proteins, assisting the formation of bone, and preventing osteoporosis. Vitamin K1 is found naturally in seaweed, liver and some vegetables, while vitamin K2 is found in fermented food products such as cheese and miso. Nattō has very large amounts of vitamin K2, approximately 870 micrograms per 100 grams of nattō.

According to a study fermented soybeans, such as natto, contains Vitamin PQQ, which is very important for the skin. PQQ existing in human tissues is derived mainly from diet.

According to the recent studies, polyamine suppresses excessive immune reactions, and natto contains a much larger amount of it than any other food. Dietary supplements containing the substances extracted from natto such as polyamine, nattokinase, FAS and vitamin K2 are available.

Nattō also contains many chemicals alleged to prevent cancer, as for example daidzein, genistein, isoflavone, phytoestrogen, and the chemical element selenium. However, most of these chemicals can also be found in other soy bean products, and their effect on cancer prevention is uncertain at best. Recent studies show nattō may have a cholesterol-lowering effect.

Nattō is also said to have an antibiotic effect, and its use as medicine against dysentery was researched by the Imperial Japanese Navy before World War II.

Nattō is claimed to prevent obesity, possibly due to a low calorie content of approximately 90 calories per 7-8 grams of protein in an average serving. Unverified claims include improved digestion, reduced effects of aging, and the reversal of hair loss in men due to its phytoestrogen content, which can lower testosterone that can cause baldness. These conjectured physiological effects of eating natto are based on biochemically active contents of nattō, and have not been confirmed by human study.

Nattō is also sometimes used as an ingredient of pet food, and it is claimed that this improves the health of the pets.
Source: Wikipedia